Oral care products such as toothpastes are routinely used by consumers as part of their oral care hygiene regimens. It is well known that oral care products can provide both therapeutic and cosmetic hygiene benefits to consumers. Therapeutic benefits include caries prevention which is typically delivered through the use of various fluoride salts; gingivitis prevention by the use of an antimicrobial agent such as triclosan, stannous fluoride, zinc citrate or essential oils; or hypersensitivity control through the use of ingredients such as strontium chloride or potassium nitrate. Cosmetic benefits provided by oral products include the control of plaque and calculus formation, removal and prevention of tooth stain, tooth whitening, breath freshening, and overall improvements in mouth feel impression which can be broadly characterized as mouth feel aesthetics.
In addition to the above mentioned therapeutic and cosmetic benefits oral care products can be used as a vehicle to deliver other benefits. The present inventors have surprisingly discovered additional important benefits of oral compositions comprising certain chemical agents that have affinity for the tooth surface. These agents either bind to the tooth surface or form insoluble compounds or complexes on the tooth surface, thereby forming a protective film or coating on the tooth surface. As a result of these protective coatings, teeth are provided with remarkable resistance and protection against dental erosion challenges for extended periods of time following use of the composition containing these agents.
Dental erosion is a permanent loss of tooth substance from the surface by the action of chemicals, such as harsh abrasives and acids, as opposed to subsurface demineralization or caries caused by bacterial action. Dental erosion is a condition that does not involve plaque bacteria and is therefore distinct from dental caries, which is a disease caused by acids generated by plaque bacteria. Dental erosion may be caused by extrinsic or intrinsic factors. Extrinsic erosion is the result of oral consumption of dietary acids such as acidic beverages or fruit juices and environmental factors such as exposure to airborne contamination or acidic water in swimming pools. Intrinsic erosion is caused for example by endogeous acids produced in the stomach and which contact the teeth during the processes of vomiting, regurgitation or reflux. The main cause of regurgitation and induced vomiting are eating disorder conditions such as nervous vomiting, anorexia or bulimia (Moss, 1998, Int. Den. J., 48, 529).
The incidence and severity of dental erosion is on the rise with the increase in the consumption of acidic beverages and juices. The pH and titratable acidity of acidic beverages have been identified as the main causative agents in the initiation and progression of dental erosion (Lussi, 1995, Caries Res. 29, 349). Thus methods have been disclosed to modify acidic food and beverage products in order to prevent their erosive effect on teeth. See for example, U.S. Pat. No. 5,108,761 and WO 01/52796 both assigned to The Procter & Gamble Company; U.S. Pat. Nos. 6,383,473; 6,319,490; WO 01/72144; and WO 00/13531 all assigned to SmithKline Beecham; CA 1018393 assigned to General Foods Corporation; U.S. Pat. No. 3,471,613 and BE 638645, both assigned to Colonial Sugar Refining Co; and U.S. Pat. No. 4,853,237 assigned to Sinebrychoff Oy. In addition there have been disclosures of oral care compositions comprising agents indicated to provide teeth with antierosion or acid resistance benefits. See for example, JP 2001/158725; U.S. Pat. Nos. 4,363,794 and 4,335,102 all assigned to Lion Corporation; U.S. Pat. No. 5,130,123 assigned to The University of Melbourne; WO 99/08550 and WO 97/30601 both assigned to SmithKline Beecham; U.S. Pat. No. 3,914,404, assigned to Dow Chemical Co.; and U.S. Pat. No. 3,105,798, assigned to The Procter & Gamble Co.
Because of the nearly epidemic incidence of dental erosion problems, there is a continuing need for improved products that provide immediate as well as sustained protection against dental erosion challenges. The present inventors have discovered that such immediate and sustained protection can be provided by the use of oral care products comprising polymeric mineral surface active agents such as polyphosphates that bind to teeth, or metal ions such as stannous, zinc or copper that form insoluble compounds that deposit onto teeth, and combinations thereof. The polymeric coating or insoluble precipitate deposited onto teeth act as a protective layer that prevents erosive chemicals from contacting the tooth surface and etching away tooth hard tissue.